1. Technical Field
The present invention relates to alight scanner for drawing or the like by light scanning, and an image forming apparatus including the light scanner.
2. Related Art
In related art, as disclosed in Patent Document 1 (JP-A-8-322227), an electromagnetic actuator having a function as a light scanner has been known. The electromagnetic actuator includes an insulating substrate on which a pair of permanent magnets are provided and a scanner main body located between the pair of permanent magnets and supported by the insulating substrate, and the scanner main body has the so-called gimbal structure having a frame-shaped support part, a frame-shaped outer movable plate provided inside of the support part, an inner movable plate with a total reflection mirror provided inside of the outer movable plate. Further, the outer movable plate is connected to the support part via a pair of first torsion bars, and the inner movable plate is connected to the outer movable plate via a pair of second torsion bars orthogonal to the first torsion bars. Furthermore, a planar coil is provided on each of the outer movable plate and the inner movable plate.
In the electromagnetic actuator having the above described configuration, magnetic fields generated from the respective planar coils by energization and a magnetic field between the pair of permanent magnets are allowed to act, and the outer movable plate rotates with the inner movable plate around the first torsion bar as a center axis, and the inner movable plate rotates around the second torsion bar as a center axis. Thereby, the electromagnetic actuator can control the reflection direction of light entering the total reflection mirror and functions as a light scanner.
However, in related art, in the electromagnetic actuator, as the first torsion bar rotates, the extension orientation of the center axis of the second torsion bar also rotates and moves. Accordingly, control for directing the total reflection mirror in a predetermined direction by respectively rotating the first torsion bar and the second torsion bar is complex. Further, the magnetic field generated from the planar coil provided on the outer movable plate of the electromagnetic actuator and the magnetic field generated from the planar coil provided on the inner movable plate may easily interfere with each other, and, in that case, the rotation of the total reflection mirror around the center axis of the first torsion bar or the second torsion bar may be different from the intended rotation. Therefore, in the light scanner having the configuration like the electromagnetic actuator in related art, there has been a problem that it is difficult and uneasy to stably and freely rotate the total reflection mirror of the inner movable plate.